1. Field of the Invention
The invention is concerned with a device for applying and dosing liquid or pasty substances onto moving surfaces, such as paper or cardboard webs, for example. Preferably, the inventive device takes the form of an application or dosage roll.
2. Background Technology
The amount of pasty substance applied to a moving web from an application or dosing roll can generally be controlled by the following measures:
a) by changing the gap between two cooperating rolls; PA1 b) by having a difference between the velocities of two cooperating rolls; and/or PA1 c) with the aid of a blade pressed on the roll with variable force.
Volumetric control of the amount of substance applied is not possible. This means that, by having an appropriate gap width, for example, between two cooperating rolls, the amount applied is controlled by the cross-section of the particular gap section.
Other application methods involve rolls with small surface cups from which excess substance is scraped off to a predetermined height, as well as a pair of rolls, of which one has a desired surface profile. In this case, the gap between the rolls can be adjusted. However, in order to obtain variable volumetric control of the amount applied, it is necessary to change rolls which, of course, involves interruption of production.